To use TheBlu, you'll have to register, and once you start using it, you'll realize that it's much more than just a screensaver. Not only can you link your Facebook account to take advantage of its social aspect, but you can also interact with other users.
The best and most interesting part, however, is that it also includes a game where you can catch fish and see information about each one. You can earn coins to purchase items and much more.
TheBlu is a beautiful screensaver that includes a lot of extra features. It's a different kind of social experience that's worth a try.